Use [CX_DB_Live]
GO
--since we want to backup DMK and want to restore it in 
--different server, I am removing encryption by SMK
--as SMK is instance based, it may be possible that
--you are trying to restore database in different instance
ALTER MASTER KEY DROP ENCRYPTION BY SERVICE MASTER KEY;

--again opening master key before taking up backup
OPEN MASTER KEY DECRYPTION BY PASSWORD = 'cxVirtualDmKey'

--backing up master key to physical file
BACKUP MASTER KEY TO FILE = 'D:\ShareLoc\CX_DB_Live_TESTDB.DMK'
ENCRYPTION BY PASSWORD='cxVirtualDmKey'
GO

--now backing up database CX_DB_Live
BACKUP DATABASE CX_DB_Live
  TO DISK = 'D:\ShareLoc\CX_DB_Live_188_02_Oct_2010_11_AM.bak' 
GO

ALTER MASTER KEY ADD ENCRYPTION BY SERVICE MASTER KEY;

